The present invention is directed to a method and apparatus for adjusting the alignment of a vehicle mounted radar.
Radar systems are used to detect objects within the radar field of view and determine distances, directions, and/or velocities. In motor vehicle applications, radar system uses include spacing, collision warning, and automatic speed control. After detecting vehicles or other objects within the radar field of view, known path prediction software may identify target vehicles in the path of the host vehicle, generate warnings to the driver, and/or suggest corrective action, such as altering the relative range and velocity of the host and target vehicles via throttle or brake control.
A basic characteristic common to these applications is that the radar system, or more precisely, its directional antenna should be properly aligned with a desired principal beam direction. In the case of a motor vehicle application, the principal beam direction is often selected to be parallel to the travel or thrust axis of the vehicle. A variety of alignment techniques may be used to align a radar""s principal beam direction with the vehicle thrust axis. One such technique includes conducting bench measurements of the radar prior to installation and then further bench measurements during installation or alignment correction. By way of example, the technique illustrated in FIG. 7 first uses a radar test bench to determine the elevation and azimuth between a reference axis 102 for a mirror fixed to the radar and the radar""s principal beam direction (also commonly referred to as a radar electrical axis). The elevation and azimuth angles are stored in radar memory and referred to below as a mirror offset angle. During radar installation or realignment, the position of the radar is set so that the angle between the mirror axis 102 and the vehicle thrust axis 106 equals the stored offset. As a result, the principal beam direction is aligned with the vehicle thrust axis.
More particularly, during or prior to radar mounting on the vehicle, and with the known mirror offset angle described above, the vehicle thrust axis 106 is determined, such as by measuring the median axis of the driven wheels on a dedicated bench that sets or checks wheel parallelism or alignment. An autocolimator 108, having a laser or optical device 110, is offset an angle 112 from thrust axis 106. The angle 112 is measurable by the autocolimator. The mirror reflects the beam generated by the laser device 110 and the autocolimator measures the reflection angle 114 which is bisected by the mirror axis 102. Thus, the measured reflection angle 114 is a function of the mirror angle 118 measured from the thrust axis 106. By positioning the radar such that the calculatable mirror angle 118 equals the stored mirror offset angle, the principal beam direction is aligned with the vehicle thrust axis 106.
The above technique, as well as other techniques available in the art, require expensive machines and well trained technicians for proper radar alignment. Due to the cost of the machines, radar alignment is commonly provided at vehicle manufacturing facilities rather than at retail dealerships. However, the alignment of the radar should also be readily adjustable after the radar system is installed in a vehicle mounting apparatus so as to permit correction of misalignments that may occur throughout the service life of the vehicle. Unfortunately, the complexity and cost of available alignment techniques do not adequately address this need.
Many conventional vehicle radar systems and associated software periodically calculate a misalignment value for the radar. For small magnitudes of misalignment, existing systems commonly correct the alignment through mathematical calibration techniques. However, large misalignments require intervention of the type described above by a technician at a service shop or factory.
In view of the above, the present invention is generally directed to providing an improved, simple, reliable and inexpensive method for adjusting radar misalignment. One feature of the method identifies when technician intervention is required for aligning the directional radar antenna. Further features of the invention include a mapping table that correlates mounting assembly adjustment manipulations to specific misalignment angles so that the necessary re-alignment may be efficiently identified and performed by a technician.
The method of correcting the radar misalignment at service shop is based on storing the estimated misalignment angle and displaying an alignment notice to the driven when the antenna misalignment exceeds a predetermined threshold. Further, the technician in the service shop is provided with a mapping table correlating misalignment angles to specific corrective action, e.g., an amount of clockwise or counter clockwise rotation of an adjustment mechanism on the vehicle mounting assembly. The method and apparatus of the present invention simplifies the identification and implementation of radar antenna alignment at the service shop.
Further scope of applicability of the present invention will become apparent from the following detailed description, claims, and drawings. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.